Prior to the present invention, I invented a certain printing apparatus described in U.S. patent application Ser. No. 30,635, filed June 16, 1980, the specification of which is hereby incorporated herein by reference and made a part hereof as if recited herein in full. The previous apparatus comprised, generally a curved printing platform, a curved screen frame including a system for attaching a printing screen to the screen frame, and a cap clamping and stretching assembly. Since the introduction of the apparatus of the previous application certain improvements have been made to the apparatus.